NIRS help to investigate diving physiology in the brain

By Sabrina Brigadoi and Dani Forster.

A novel wearable NIRS device has been developed by a team at University of St Andrews (St Andrews, Scotland) with the aim to investigate diving physiology in the brain and blubber of mammalians (harbor seals). This work has been recently highlighted on the BBC Science Focus Magazine (https://www.sciencefocus.com/news/seals-use-thought-to-prepare-body-for-diving/).

The advent of NIRS wearable devices can open up new interesting scenarios and fields for optical neuroimaging. A feature story in the BBC Science Focus Magazine, dated 22nd June 2019, highlighted recent work at the University of St Andrews, United Kingdom, using NIRS to investigate diving physiology of seal harbors. This investigation was not possible before because there existed no device able to track hemodynamic and oxygenation changes in live seals while they were swimming. Wearable NIRS can overcome this limitation and provide access to this interesting information.

The team, headed by Dr. McKnight, discovered that seals exert cognitive control over the preparatory physiological response that helps them to stay underwater for long periods. In particular, seals constrict their peripheral blood vessels, thus increasing cerebral blood flow, approximately 15 seconds before submersion. This physiological response is not, therefore, a simple reflex response, but it is under brain control. Furthermore, seals seem able to increase their cerebral oxygenation during diving at a constant time, while still underwater.

This research highlights that it could be feasible to study mammalians’ brain non-invasively when they are in open ocean, swimming for long periods of time and at considerable depths, with likely very low heart rate, but yet with no brain injuries. These investigations could open up new exciting discoveries about how it is possible to exert cognitive control over physiology in extreme conditions and preserving brain functionality.